From 6d0c3e23372bbf915015e7c5d8fa46bffc3354c4 Mon Sep 17 00:00:00 2001
From: Macdara <m4cd4r4@gmail.com>
Date: Wed, 25 Mar 2026 13:33:06 +0000
Subject: [PATCH] feat: add code autocomplete to CodeMirror editor

Adds Ctrl+Space autocomplete using CodeMirror show-hint addon.
Provides completions from user-defined snippets and document words.

Fixes #2567
IssueHunt: https://oss.issuehunt.io/r/BoostIo/Boostnote/issues/2567
---
 browser/components/CodeEditor.js   | 75 ++++++++++++++++++++++++++++++
 browser/components/CodeEditor.styl | 31 ++++++++++++
 2 files changed, 106 insertions(+)

diff --git a/browser/components/CodeEditor.js b/browser/components/CodeEditor.js
index 27ee4271e..488e86a86 100644
--- a/browser/components/CodeEditor.js
+++ b/browser/components/CodeEditor.js
@@ -2,6 +2,9 @@ import PropTypes from 'prop-types'
 import React from 'react'
 import _ from 'lodash'
 import CodeMirror from 'codemirror'
+import 'codemirror/addon/hint/show-hint'
+import 'codemirror/addon/hint/show-hint.css'
+import 'codemirror/addon/hint/anyword-hint'
 import hljs from 'highlight.js'
 import 'codemirror-mode-elixir'
 import attachmentManagement from 'browser/main/lib/dataApi/attachmentManagement'
@@ -233,6 +236,17 @@ export default class CodeEditor extends React.Component {
       'Cmd-T': function(cm) {
         // Do nothing
       },
+      'Ctrl-Space': function(cm) {
+        const hints = self.getSnippetHints(cm)
+        if (hints) {
+          cm.showHint({
+            hint: function() {
+              return self.getSnippetHints(cm)
+            },
+            completeSingle: false
+          })
+        }
+      },
       [translateHotkey(hotkey.insertDate)]: function(cm) {
         const dateNow = new Date()
         if (self.props.dateFormatISO8601) {
@@ -569,6 +583,67 @@ export default class CodeEditor extends React.Component {
     }
   }
 
+  getSnippetHints(cm) {
+    const cursor = cm.getCursor()
+    const line = cm.getLine(cursor.line)
+    const end = cursor.ch
+    let start = end
+
+    while (start > 0 && /\w/.test(line.charAt(start - 1))) {
+      start--
+    }
+
+    const currentWord = line.slice(start, end)
+    if (currentWord.length === 0) {
+      return null
+    }
+
+    const lowerWord = currentWord.toLowerCase()
+    const list = []
+    const seen = new Set()
+
+    const snippets = snippetManager.snippets || []
+    for (let i = 0; i < snippets.length; i++) {
+      const snippet = snippets[i]
+      const prefixes = snippet.prefix || []
+      for (let j = 0; j < prefixes.length; j++) {
+        const prefix = prefixes[j]
+        if (
+          prefix.toLowerCase().indexOf(lowerWord) === 0 &&
+          !seen.has(prefix)
+        ) {
+          seen.add(prefix)
+          list.push({
+            text: snippet.content.replace(/:\{\}/g, ''),
+            displayText: prefix + ' (snippet: ' + snippet.name + ')',
+            className: 'snippet-hint'
+          })
+        }
+      }
+    }
+
+    const anywordResult = CodeMirror.hint.anyword(cm)
+    if (anywordResult && anywordResult.list) {
+      for (let i = 0; i < anywordResult.list.length; i++) {
+        const word = anywordResult.list[i]
+        if (!seen.has(word)) {
+          seen.add(word)
+          list.push(word)
+        }
+      }
+    }
+
+    if (list.length === 0) {
+      return null
+    }
+
+    return {
+      list: list,
+      from: CodeMirror.Pos(cursor.line, start),
+      to: CodeMirror.Pos(cursor.line, end)
+    }
+  }
+
   quitEditor() {
     document.querySelector('textarea').blur()
   }
diff --git a/browser/components/CodeEditor.styl b/browser/components/CodeEditor.styl
index 1aa0e466b..bb4f0fc09 100644
--- a/browser/components/CodeEditor.styl
+++ b/browser/components/CodeEditor.styl
@@ -3,3 +3,34 @@
 
 .spellcheck-select
   border: none
+
+.CodeMirror-hints
+  position absolute
+  z-index 100
+  overflow hidden
+  list-style none
+  margin 0
+  padding 2px
+  box-shadow 2px 3px 5px rgba(0, 0, 0, 0.2)
+  border-radius 3px
+  border 1px solid silver
+  background white
+  font-size 90%
+  font-family monospace
+  max-height 20em
+  overflow-y auto
+
+.CodeMirror-hint
+  margin 0
+  padding 0 4px
+  border-radius 2px
+  white-space pre
+  color black
+  cursor pointer
+
+li.CodeMirror-hint-active
+  background #08f
+  color white
+
+.snippet-hint
+  font-style italic